The purpose of this project is screen volunteers for protocols that involve administration of investigational agents and to collect human specimens, such as blood, mucosal secretions, skin swabs, skin biopsy, or body fluids, and in some circumstances perform radiographic imaging and clinical evaluations, to support laboratory research studies and to validate research assays used in evaluation of clinical trials immunogenicity results. These samples will be used by laboratory researchers in their work on the development of vaccines for HIV and other infectious diseases, to study the correlates of immunity related to infectious diseases, and in laboratory work related to the development and/or validation of immunological assays. In order to carry out research studies, it is sometimes necessary to obtain larger quantities of plasma or mononuclear cells than can be safely obtained by simple phlebotomy. These components can be safely obtained using apheresis procedures, which are performed in the NIH Clinical Center Department of Transfusion Medicine (DTM).